Patents by Inventor Hamid Jafarkhani

Hamid Jafarkhani has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20070093274
    Abstract: A multiple antenna wireless system including a transmitter and a receiver comprises a reconfigurable large antenna array having a plurality of antennas. A plurality of RF chains in the transmitter is coupled to the reconfigurable large antenna array. A pilot assisted round robin channel estimation means tracks the fading channel; and an adaptive round robin transmit beamforming means beam forms the reconfigurable large antenna array. A method for multiple antenna wireless communication comprising the steps of tracking a plurality of fading channels in a reconfigurable large antenna array having a plurality of antennas using pilot assisted round robin channel estimation to selectively couple a plurality of RF chains in the transmitter to the reconfigurable large antenna array, and adaptively, round-robin transmit beamforming the reconfigurable large antenna array.
    Type: Application
    Filed: October 23, 2006
    Publication date: April 26, 2007
    Inventors: Hamid Jafarkhani, Li Liu
  • Patent number: 7164729
    Abstract: Input signals of each frame are encoded by mapping the signals onto a coordinate system dictated by the symbols of the previous frame, and symbols from a constellation are selected based on the results of such mapping. Received signals are detected by preprocessing the signals detected at each antenna with signals detected by the antenna at the immediately previous frame, and then applied to a maximum likelihood detector circuit, followed by an inverse mapping circuit.
    Type: Grant
    Filed: March 24, 2005
    Date of Patent: January 16, 2007
    Assignee: AT&T Corp.
    Inventors: Hamid Jafarkhani, Vahid Tarokh
  • Patent number: 7154970
    Abstract: Input signals of each frame are encoded by mapping the signals onto a coordinate system dictated by the symbols of the previous frame, and symbols from a constellation are selected based on the results of such mapping. Received signals are detected by preprocessing the signals detected at each antenna with signals detected by the antenna at the immediately previous frame, and then applied to a maximum likelihood detector circuit, followed by an inverse mapping circuit.
    Type: Grant
    Filed: September 13, 2005
    Date of Patent: December 26, 2006
    Assignee: AT&T Corp.
    Inventors: Hamid Jafarkhani, Vahid Tarokh
  • Publication number: 20060222101
    Abstract: An adaptive MIMO communications system includes a multifunctional reconfigurable antenna with a selectively alterable effective physical antenna array configuration and radiation/polarization properties, which configuration and properties is a component in the optimization of the adaptive system parameters. The multifunctional reconfigurable antenna comprises a plurality of antenna components and a plurality of selectively controllable switches coupling selected ones of the plurality of antenna components together into a multifunctional reconfigurable subarray of antenna components. A processing unit coupled to the multifunctional reconfigurable antenna determines communication channel conditions for generating adaptive control signals to the plurality of selectively controllable switches to selectively apply a selected space-time coding protocol or a selected beam forming protocol together on the plurality of antenna components depending on channel conditions.
    Type: Application
    Filed: November 22, 2005
    Publication date: October 5, 2006
    Inventors: Bedri Cetiner, Hamid Jafarkhani
  • Publication number: 20060176977
    Abstract: A method for MIMO wireless communication comprises the steps of generating inner and outer codes based on channel state information available at a transmitter and concatenating different inner codes with different outer codes; and using the generated concatenated inner and outer codes for wireless communication. The inner and outer codes are based on channel phase information at the transmitter or channel feedback. High-performance trellis codes or block codes for use in cellular networks are illustratively described. The space-time trellis codes are generated by set partitioning on a plurality of classes of signal designs to generate a series of inner codes, each of the series of inner codes being optimized by channel phase feedback, and concatenating each inner code with a multiple trellis coded modulated outer code to provide a complete space-time trellis code as a cophase space-time trellis code.
    Type: Application
    Filed: January 12, 2006
    Publication date: August 10, 2006
    Inventors: Hamid Jafarkhani, Li Liu
  • Publication number: 20060159199
    Abstract: A super set of orthogonal space-time block codes is combined with set partitioning to form super-orthogonal space-time trellis codes having full diversity, enhanced coding gains, and improved rates. In communications systems, these codes are implemented by an encoder of a diverse transmitter to send an information signal to a receiver having one or more receiver elements. A decoder in the receiver decodes the encoded signal to reproduce the information signal. A method of the invention is used to generate set portioning structures and trellis structures that enable code designers to systematically design the codes of the invention.
    Type: Application
    Filed: March 20, 2006
    Publication date: July 20, 2006
    Applicant: Broadcom Corporation
    Inventors: Nambirajan Seshadri, Hamid Jafarkhani
  • Patent number: 7065148
    Abstract: A super set of space-time block codes is combined with set partitioning to form super-orthogonal space-time trellis codes having full diversity, enhanced coding gains, and improved rates. In communications systems, these codes are implemented by an encoder of a diverse transmitter to send an information signal to a receiver having one or more receiver elements. A decoder in the receiver decodes the encoded signal to reproduce the information signal. A method of the invention is used to generate set partitioning structures and trellis structures that enable code designers to systematically design the codes of the invention.
    Type: Grant
    Filed: November 6, 2001
    Date of Patent: June 20, 2006
    Assignee: Broadcom Corporation
    Inventors: Nambirajan Seshadri, Hamid Jafarkhani
  • Publication number: 20050163246
    Abstract: Input signals of each frame are encoded by mapping the signals onto a coordinate system dictated by the symbols of the previous frame, and symbols from a constellation are selected based on the results of such mapping. Received signals are detected by preprocessing the signals detected at each antenna with signals detected by the antenna at the immediately previous frame, and then applied to a maximum likelihood detector circuit, followed by an inverse mapping circuit.
    Type: Application
    Filed: March 24, 2005
    Publication date: July 28, 2005
    Inventors: Hamid Jafarkhani, Vahid Tarokh
  • Patent number: 6920177
    Abstract: A method and apparatus for utilizing temporal prediction and motion compensated prediction to accomplish multiple description video coding is disclosed. An encoder receives a sequence of video frames and divides each frame into non-overlapping macroblocks. Each macroblock is then encoded using either an intraframe mode (I-mode) or a prediction mode (P-mode) technique. Both the I-mode and the P-mode encoding techniques produce an output for each of n channels used to transmit the encoded video data to a decoder. The P-mode technique generates at least n+1 prediction error signals for each macroblock.
    Type: Grant
    Filed: January 23, 2003
    Date of Patent: July 19, 2005
    Assignee: AT&T Corp.
    Inventors: Michael Orchard, Hamid Jafarkhani, Amy Reibman, Yao Wang
  • Publication number: 20050152456
    Abstract: A method and apparatus for utilizing temporal prediction and motion compensated prediction to accomplish multiple description video coding is disclosed. An encoder receives a sequence of video frames and divides each frame into non-overlapping macroblocks. Each macroblock is then encoded using either an intraframe mode (I-mode) or a prediction mode (P-mode) technique. Both the I-mode and the P-mode encoding techniques produce an output for each of n channels used to transmit the encoded video data to a decoder. The P-mode technique generates at least n+1 prediction error signals for each macroblock. One of the at least n+1 P-mode prediction error signals is encoded such that it may be utilized to reconstruct the original sequence of video frames regardless of the number of channels received by the decoder. A component of the one of the at least n+1 P-mode prediction error signals is sent on each of the n channels.
    Type: Application
    Filed: February 3, 2005
    Publication date: July 14, 2005
    Inventors: Michael Orchard, Hamid Jafarkhani, Amy Reibman, Yao Wang
  • Patent number: 6891903
    Abstract: A differential detection approach allows communication without knowing the channel parameters, where the transmitter can include a plurality of transmitting antennas in excess of two. In the transmitter, each block of bits is mapped to a vector that is processed to develop a symbols vector, by employing mutually orthogonal vectors and the symbols vector of the previous block. The symbols vector is applied to a space-time mapping block, and thence to transmitting antennas. At the receiver, the received signals of a block are formed into vector, which is combined with a corresponding vector from the previous block in accordance with the mutually orthogonal vectors. The combined vector is summed with combined vectors of the other receive antennas, and the summed result is applied to a minimum distance decoder module. The decoder module selects a “most likely ” vector, and that vector is applied to a mapping that recovers the transmitted bits.
    Type: Grant
    Filed: April 27, 2001
    Date of Patent: May 10, 2005
    Assignee: AT&T Corp.
    Inventors: Hamid Jafarkhani, Vahid Tarokh
  • Patent number: 6823018
    Abstract: A method and apparatus reliably encode and decode information over a communication system. The method includes transforming two coefficients into two pairs of random variables, one random variable in each pair having substantially equal energy as one random variable in the other pair. The method further includes quantizing each of the pairs of random variables and entropy coding each quantized random variable separately creating an encoded bitstreams. The encoded bitstreams are received by a decoder which first determines which channels of the communication system are working. The encoded bitstream is entropy decoded, inversed quantized and inversed transformed. An inverse transform performs three different transformations depending upon which channels are working, i.e., whether the first, second or both channels are working.
    Type: Grant
    Filed: February 23, 2000
    Date of Patent: November 23, 2004
    Assignee: AT&T Corp.
    Inventors: Hamid Jafarkhani, Michael T. Orchard, Amy R. Reibman, Yao Wang
  • Patent number: 6798911
    Abstract: An approach to clustering a set of images based on similarity measures employs a fuzzy clustering paradigm in which each image is represented by a node in a graph. The graph is ultimately partitioned into subgraphs, each of which represent true clusters among which the various images are distributed. The partitioning is performed in a series of stages by identifying one true cluster at each stage, and removing the nodes belonging to each identified true cluster from further consideration so that the remaining, unclustered nodes may then be grouped. At the beginning of each such stage, the nodes that remain to be clustered are treated as all belonging to a single candidate cluster. Nodes are removed from this single candidate cluster in accordance with similarity and connectivity criteria, to arrive at a true cluster. The member nodes of this true cluster are then removed from further consideration, prior to the next stage in the process.
    Type: Grant
    Filed: March 28, 2001
    Date of Patent: September 28, 2004
    Assignee: AT&T Corp.
    Inventors: Hamid Jafarkhani, Vahid Tarokh
  • Patent number: 6661856
    Abstract: The prior art teachings for encoding signals and transmitting them over a plurality of antennas are advanced by disclosing a method for encoding for any number of transmitting antennas.
    Type: Grant
    Filed: March 21, 2000
    Date of Patent: December 9, 2003
    Assignee: AT&T
    Inventors: Arthur R. Calderbank, Hamid Jafarkhani, Ayman F. Naguib, Nambirajan Seshadri, Vahid Tarokh
  • Publication number: 20030138047
    Abstract: A method and apparatus for utilizing temporal prediction and motion compensated prediction to accomplish multiple description video coding is disclosed. An encoder receives a sequence of video frames and divides each frame into non-overlapping macroblocks. Each macroblock is then encoded using either an intraframe mode (I-mode) or a prediction mode (P-mode) technique. Both the I-mode and the P-mode encoding techniques produce an output for each of n channels used to transmit the encoded video data to a decoder. The P-mode technique generates at least n+1 prediction error signals for each macroblock. One of the at least n+1 P-mode prediction error signals is encoded such that it may be utilized to reconstruct the original sequence of video frames regardless of the number of channels received by the decoder. A component of the one of the at least n+1 P-mode prediction error signals is sent on each of the n channels.
    Type: Application
    Filed: January 23, 2003
    Publication date: July 24, 2003
    Inventors: Michael Orchard, Hamid Jafarkhani, Amy Reibman, Yao Wang
  • Patent number: 6587515
    Abstract: Input signals of each frame are encoded by mapping the signals onto a coordinate system dictated by the symbols of the previous frame, and symbols from a constellation are selected based on the results of such mapping. Received signals are detected by preprocessing the signals detected at each antenna with signals detected by the antenna at the immediately previous frame, and then applied to a maximum likelihood detector circuit, followed by an inverse mapping circuit.
    Type: Grant
    Filed: April 22, 1999
    Date of Patent: July 1, 2003
    Inventors: Hamid Jafarkhani, Vahid Tarokh
  • Patent number: 6556624
    Abstract: A method and apparatus for utilizing temporal prediction and motion compensated prediction to accomplish multiple description video coding is disclosed. An encoder receives a sequence of video frames and divides each frame into non-overlapping macroblocks. Each macroblock is then encoded using either an intraframe mode (I-mode) or a prediction mode (P-mode) technique. Both the I-mode and the P-mode encoding techniques produce an output for each of n channels used to transmit the encoded video data to a decoder. The P-mode technique generates at least n+1 prediction error signals for each macroblock. One of the at least n+1 P-mode prediction error signals is encoded such that it may be utilized to reconstruct the original sequence of video frames regardless of the number of channels received by the decoder. A component of the one of the at least n+1 P-mode prediction error signals is sent on each of the n channels.
    Type: Grant
    Filed: January 5, 2000
    Date of Patent: April 29, 2003
    Assignee: AT&T Corp.
    Inventors: Michael Orchard, Hamid Jafarkhani, Amy Reibman, Yao Wang
  • Patent number: 6542619
    Abstract: A method and system for recognizing scene changes in digitized video is based on using one-dimensional projections from the recorded video. Wavelet transformation is applied on each projection to determine the high frequency components. These components are then auto-correlated and a time-based curve of the autocorrelation coefficients is generated. A decision is made to define a “scene change” when the autocorrelation coefficient curves are greater than a predetermined value.
    Type: Grant
    Filed: April 13, 2000
    Date of Patent: April 1, 2003
    Assignee: AT&T Corp.
    Inventors: Hamid Jafarkhani, Behzad Shahraray
  • Patent number: 6542554
    Abstract: A multiple description TCQ arrangement employs a trellis graph that is the tensor product of two trellis graphs. The codevectors of the tensor-product trellis, ci, are incorporated within trellis graph T1 and also within trellis graph T2. The incorporation within trellis graph T1 is effected by assigning the ci codevectors to sets, and by deriving therefrom codevectors for trellis graphs T1 and T2. The actual values that these codevectors take on are arranged to insure certain distortion results. Consequently, an improved arrangement is realized in which, two encoders are cooperatively generating separate trellis-coded descriptions of the input sequence. Three different fidelity levels can thus be achieved, which allows for use of receivers that are responsive to different rates, or the use of receivers that have adaptable rates.
    Type: Grant
    Filed: March 23, 2001
    Date of Patent: April 1, 2003
    Assignee: AT&T Corp.
    Inventors: Hamid Jafarkhani, Vahid Tarokh
  • Patent number: 6445747
    Abstract: A system and method to reduce a ratio between a peak signal power and an average power (PAPR) in a multi-tone communication system. The system includes an encoder configured to receive a plurality of input bits and to generate a plurality of coded symbols based on the plurality of input bits, and a phase shift calculator configured to calculate a plurality of phase shift values for the coded symbols that minimizes the peak to average power ratio. The system further includes an encoding phase shifter coupled to the encoder and the phase shift calculator, configured to receive the phase shift values from the phase shift calculator and configured to phase shift the plurality of coded symbols to generate a plurality of phase shifted symbols.
    Type: Grant
    Filed: December 31, 1998
    Date of Patent: September 3, 2002
    Assignee: AT&T Corporation
    Inventors: Hamid Jafarkhani, Vahid Tarokh